1 /*
2 * Xen SCSI frontend driver
3 *
4 * Copyright (c) 2008, FUJITSU Limited
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version 2
8 * as published by the Free Software Foundation; or, when distributed
9 * separately from the Linux kernel or incorporated into other
10 * software packages, subject to the following license:
11 *
12 * Permission is hereby granted, free of charge, to any person obtaining a copy
13 * of this source file (the "Software"), to deal in the Software without
14 * restriction, including without limitation the rights to use, copy, modify,
15 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
16 * and to permit persons to whom the Software is furnished to do so, subject to
17 * the following conditions:
18 *
19 * The above copyright notice and this permission notice shall be included in
20 * all copies or substantial portions of the Software.
21 *
22 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
23 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
24 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
25 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
26 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
27 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
28 * IN THE SOFTWARE.
29 */
30
31 #include <linux/module.h>
32 #include <linux/kernel.h>
33 #include <linux/device.h>
34 #include <linux/wait.h>
35 #include <linux/interrupt.h>
36 #include <linux/mutex.h>
37 #include <linux/spinlock.h>
38 #include <linux/sched.h>
39 #include <linux/blkdev.h>
40 #include <linux/pfn.h>
41 #include <linux/slab.h>
42 #include <linux/bitops.h>
43
44 #include <scsi/scsi_cmnd.h>
45 #include <scsi/scsi_device.h>
46 #include <scsi/scsi.h>
47 #include <scsi/scsi_host.h>
48
49 #include <xen/xen.h>
50 #include <xen/xenbus.h>
51 #include <xen/grant_table.h>
52 #include <xen/events.h>
53 #include <xen/page.h>
54
55 #include <xen/interface/grant_table.h>
56 #include <xen/interface/io/vscsiif.h>
57 #include <xen/interface/io/protocols.h>
58
59 #include <asm/xen/hypervisor.h>
60
61 #define VSCSIFRONT_OP_ADD_LUN 1
62 #define VSCSIFRONT_OP_DEL_LUN 2
63 #define VSCSIFRONT_OP_READD_LUN 3
64
65 /* Tuning point. */
66 #define VSCSIIF_DEFAULT_CMD_PER_LUN 10
67 #define VSCSIIF_MAX_TARGET 64
68 #define VSCSIIF_MAX_LUN 255
69
70 #define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE)
71 #define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE
72
73 #define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \
74 sizeof(struct scsiif_request_segment)))
75
76 struct vscsifrnt_shadow {
77 /* command between backend and frontend */
78 unsigned char act;
79 uint8_t nr_segments;
80 uint16_t rqid;
81 uint16_t ref_rqid;
82
83 bool inflight;
84
85 unsigned int nr_grants; /* number of grants in gref[] */
86 struct scsiif_request_segment *sg; /* scatter/gather elements */
87 struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];
88
89 /* Do reset or abort function. */
90 wait_queue_head_t wq_reset; /* reset work queue */
91 int wait_reset; /* reset work queue condition */
92 int32_t rslt_reset; /* reset response status: */
93 /* SUCCESS or FAILED or: */
94 #define RSLT_RESET_WAITING 0
95 #define RSLT_RESET_ERR -1
96
97 /* Requested struct scsi_cmnd is stored from kernel. */
98 struct scsi_cmnd *sc;
99 int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
100 };
101
102 struct vscsifrnt_info {
103 struct xenbus_device *dev;
104
105 struct Scsi_Host *host;
106 enum {
107 STATE_INACTIVE,
108 STATE_ACTIVE,
109 STATE_ERROR
110 } host_active;
111
112 unsigned int evtchn;
113 unsigned int irq;
114
115 grant_ref_t ring_ref;
116 struct vscsiif_front_ring ring;
117 struct vscsiif_response ring_rsp;
118
119 spinlock_t shadow_lock;
120 DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
121 struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];
122
123 /* Following items are protected by the host lock. */
124 wait_queue_head_t wq_sync;
125 wait_queue_head_t wq_pause;
126 unsigned int wait_ring_available:1;
127 unsigned int waiting_pause:1;
128 unsigned int pause:1;
129 unsigned callers;
130
131 char dev_state_path[64];
132 struct task_struct *curr;
133 };
134
135 static DEFINE_MUTEX(scsifront_mutex);
136
scsifront_wake_up(struct vscsifrnt_info * info)137 static void scsifront_wake_up(struct vscsifrnt_info *info)
138 {
139 info->wait_ring_available = 0;
140 wake_up(&info->wq_sync);
141 }
142
scsifront_get_rqid(struct vscsifrnt_info * info)143 static int scsifront_get_rqid(struct vscsifrnt_info *info)
144 {
145 unsigned long flags;
146 int free;
147
148 spin_lock_irqsave(&info->shadow_lock, flags);
149
150 free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
151 __clear_bit(free, info->shadow_free_bitmap);
152
153 spin_unlock_irqrestore(&info->shadow_lock, flags);
154
155 return free;
156 }
157
_scsifront_put_rqid(struct vscsifrnt_info * info,uint32_t id)158 static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
159 {
160 int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
161
162 __set_bit(id, info->shadow_free_bitmap);
163 info->shadow[id] = NULL;
164
165 return empty || info->wait_ring_available;
166 }
167
scsifront_put_rqid(struct vscsifrnt_info * info,uint32_t id)168 static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id)
169 {
170 unsigned long flags;
171 int kick;
172
173 spin_lock_irqsave(&info->shadow_lock, flags);
174 kick = _scsifront_put_rqid(info, id);
175 spin_unlock_irqrestore(&info->shadow_lock, flags);
176
177 if (kick)
178 scsifront_wake_up(info);
179 }
180
scsifront_do_request(struct vscsifrnt_info * info,struct vscsifrnt_shadow * shadow)181 static int scsifront_do_request(struct vscsifrnt_info *info,
182 struct vscsifrnt_shadow *shadow)
183 {
184 struct vscsiif_front_ring *ring = &(info->ring);
185 struct vscsiif_request *ring_req;
186 struct scsi_cmnd *sc = shadow->sc;
187 uint32_t id;
188 int i, notify;
189
190 if (RING_FULL(&info->ring))
191 return -EBUSY;
192
193 id = scsifront_get_rqid(info); /* use id in response */
194 if (id >= VSCSIIF_MAX_REQS)
195 return -EBUSY;
196
197 info->shadow[id] = shadow;
198 shadow->rqid = id;
199
200 ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt);
201 ring->req_prod_pvt++;
202
203 ring_req->rqid = id;
204 ring_req->act = shadow->act;
205 ring_req->ref_rqid = shadow->ref_rqid;
206 ring_req->nr_segments = shadow->nr_segments;
207
208 ring_req->id = sc->device->id;
209 ring_req->lun = sc->device->lun;
210 ring_req->channel = sc->device->channel;
211 ring_req->cmd_len = sc->cmd_len;
212
213 BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE);
214
215 memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len);
216
217 ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction;
218 ring_req->timeout_per_command = scsi_cmd_to_rq(sc)->timeout / HZ;
219
220 for (i = 0; i < (shadow->nr_segments & ~VSCSIIF_SG_GRANT); i++)
221 ring_req->seg[i] = shadow->seg[i];
222
223 shadow->inflight = true;
224
225 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify);
226 if (notify)
227 notify_remote_via_irq(info->irq);
228
229 return 0;
230 }
231
scsifront_set_error(struct vscsifrnt_info * info,const char * msg)232 static void scsifront_set_error(struct vscsifrnt_info *info, const char *msg)
233 {
234 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME "%s\n"
235 "Disabling device for further use\n", msg);
236 info->host_active = STATE_ERROR;
237 }
238
scsifront_gnttab_done(struct vscsifrnt_info * info,struct vscsifrnt_shadow * shadow)239 static void scsifront_gnttab_done(struct vscsifrnt_info *info,
240 struct vscsifrnt_shadow *shadow)
241 {
242 int i;
243
244 if (shadow->sc->sc_data_direction == DMA_NONE)
245 return;
246
247 for (i = 0; i < shadow->nr_grants; i++) {
248 if (unlikely(!gnttab_try_end_foreign_access(shadow->gref[i]))) {
249 scsifront_set_error(info, "grant still in use by backend");
250 return;
251 }
252 }
253
254 kfree(shadow->sg);
255 }
256
scsifront_host_byte(int32_t rslt)257 static unsigned int scsifront_host_byte(int32_t rslt)
258 {
259 switch (XEN_VSCSIIF_RSLT_HOST(rslt)) {
260 case XEN_VSCSIIF_RSLT_HOST_OK:
261 return DID_OK;
262 case XEN_VSCSIIF_RSLT_HOST_NO_CONNECT:
263 return DID_NO_CONNECT;
264 case XEN_VSCSIIF_RSLT_HOST_BUS_BUSY:
265 return DID_BUS_BUSY;
266 case XEN_VSCSIIF_RSLT_HOST_TIME_OUT:
267 return DID_TIME_OUT;
268 case XEN_VSCSIIF_RSLT_HOST_BAD_TARGET:
269 return DID_BAD_TARGET;
270 case XEN_VSCSIIF_RSLT_HOST_ABORT:
271 return DID_ABORT;
272 case XEN_VSCSIIF_RSLT_HOST_PARITY:
273 return DID_PARITY;
274 case XEN_VSCSIIF_RSLT_HOST_ERROR:
275 return DID_ERROR;
276 case XEN_VSCSIIF_RSLT_HOST_RESET:
277 return DID_RESET;
278 case XEN_VSCSIIF_RSLT_HOST_BAD_INTR:
279 return DID_BAD_INTR;
280 case XEN_VSCSIIF_RSLT_HOST_PASSTHROUGH:
281 return DID_PASSTHROUGH;
282 case XEN_VSCSIIF_RSLT_HOST_SOFT_ERROR:
283 return DID_SOFT_ERROR;
284 case XEN_VSCSIIF_RSLT_HOST_IMM_RETRY:
285 return DID_IMM_RETRY;
286 case XEN_VSCSIIF_RSLT_HOST_REQUEUE:
287 return DID_REQUEUE;
288 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_DISRUPTED:
289 return DID_TRANSPORT_DISRUPTED;
290 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_FAILFAST:
291 return DID_TRANSPORT_FAILFAST;
292 case XEN_VSCSIIF_RSLT_HOST_TARGET_FAILURE:
293 return DID_TARGET_FAILURE;
294 case XEN_VSCSIIF_RSLT_HOST_NEXUS_FAILURE:
295 return DID_NEXUS_FAILURE;
296 case XEN_VSCSIIF_RSLT_HOST_ALLOC_FAILURE:
297 return DID_ALLOC_FAILURE;
298 case XEN_VSCSIIF_RSLT_HOST_MEDIUM_ERROR:
299 return DID_MEDIUM_ERROR;
300 case XEN_VSCSIIF_RSLT_HOST_TRANSPORT_MARGINAL:
301 return DID_TRANSPORT_MARGINAL;
302 default:
303 return DID_ERROR;
304 }
305 }
306
scsifront_cdb_cmd_done(struct vscsifrnt_info * info,struct vscsiif_response * ring_rsp)307 static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info,
308 struct vscsiif_response *ring_rsp)
309 {
310 struct vscsifrnt_shadow *shadow;
311 struct scsi_cmnd *sc;
312 uint32_t id;
313 uint8_t sense_len;
314
315 id = ring_rsp->rqid;
316 shadow = info->shadow[id];
317 sc = shadow->sc;
318
319 BUG_ON(sc == NULL);
320
321 scsifront_gnttab_done(info, shadow);
322 if (info->host_active == STATE_ERROR)
323 return;
324 scsifront_put_rqid(info, id);
325
326 set_host_byte(sc, scsifront_host_byte(ring_rsp->rslt));
327 set_status_byte(sc, XEN_VSCSIIF_RSLT_STATUS(ring_rsp->rslt));
328 scsi_set_resid(sc, ring_rsp->residual_len);
329
330 sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE,
331 ring_rsp->sense_len);
332
333 if (sense_len)
334 memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len);
335
336 scsi_done(sc);
337 }
338
scsifront_sync_cmd_done(struct vscsifrnt_info * info,struct vscsiif_response * ring_rsp)339 static void scsifront_sync_cmd_done(struct vscsifrnt_info *info,
340 struct vscsiif_response *ring_rsp)
341 {
342 uint16_t id = ring_rsp->rqid;
343 unsigned long flags;
344 struct vscsifrnt_shadow *shadow = info->shadow[id];
345 int kick;
346
347 spin_lock_irqsave(&info->shadow_lock, flags);
348 shadow->wait_reset = 1;
349 switch (shadow->rslt_reset) {
350 case RSLT_RESET_WAITING:
351 if (ring_rsp->rslt == XEN_VSCSIIF_RSLT_RESET_SUCCESS)
352 shadow->rslt_reset = SUCCESS;
353 else
354 shadow->rslt_reset = FAILED;
355 break;
356 case RSLT_RESET_ERR:
357 kick = _scsifront_put_rqid(info, id);
358 spin_unlock_irqrestore(&info->shadow_lock, flags);
359 kfree(shadow);
360 if (kick)
361 scsifront_wake_up(info);
362 return;
363 default:
364 scsifront_set_error(info, "bad reset state");
365 break;
366 }
367 spin_unlock_irqrestore(&info->shadow_lock, flags);
368
369 wake_up(&shadow->wq_reset);
370 }
371
scsifront_do_response(struct vscsifrnt_info * info,struct vscsiif_response * ring_rsp)372 static void scsifront_do_response(struct vscsifrnt_info *info,
373 struct vscsiif_response *ring_rsp)
374 {
375 struct vscsifrnt_shadow *shadow;
376
377 if (ring_rsp->rqid >= VSCSIIF_MAX_REQS ||
378 !info->shadow[ring_rsp->rqid]->inflight) {
379 scsifront_set_error(info, "illegal rqid returned by backend!");
380 return;
381 }
382 shadow = info->shadow[ring_rsp->rqid];
383 shadow->inflight = false;
384
385 if (shadow->act == VSCSIIF_ACT_SCSI_CDB)
386 scsifront_cdb_cmd_done(info, ring_rsp);
387 else
388 scsifront_sync_cmd_done(info, ring_rsp);
389 }
390
scsifront_ring_drain(struct vscsifrnt_info * info,unsigned int * eoiflag)391 static int scsifront_ring_drain(struct vscsifrnt_info *info,
392 unsigned int *eoiflag)
393 {
394 struct vscsiif_response ring_rsp;
395 RING_IDX i, rp;
396 int more_to_do = 0;
397
398 rp = READ_ONCE(info->ring.sring->rsp_prod);
399 virt_rmb(); /* ordering required respective to backend */
400 if (RING_RESPONSE_PROD_OVERFLOW(&info->ring, rp)) {
401 scsifront_set_error(info, "illegal number of responses");
402 return 0;
403 }
404 for (i = info->ring.rsp_cons; i != rp; i++) {
405 RING_COPY_RESPONSE(&info->ring, i, &ring_rsp);
406 scsifront_do_response(info, &ring_rsp);
407 if (info->host_active == STATE_ERROR)
408 return 0;
409 *eoiflag &= ~XEN_EOI_FLAG_SPURIOUS;
410 }
411
412 info->ring.rsp_cons = i;
413
414 if (i != info->ring.req_prod_pvt)
415 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
416 else
417 info->ring.sring->rsp_event = i + 1;
418
419 return more_to_do;
420 }
421
scsifront_cmd_done(struct vscsifrnt_info * info,unsigned int * eoiflag)422 static int scsifront_cmd_done(struct vscsifrnt_info *info,
423 unsigned int *eoiflag)
424 {
425 int more_to_do;
426 unsigned long flags;
427
428 spin_lock_irqsave(info->host->host_lock, flags);
429
430 more_to_do = scsifront_ring_drain(info, eoiflag);
431
432 info->wait_ring_available = 0;
433
434 spin_unlock_irqrestore(info->host->host_lock, flags);
435
436 wake_up(&info->wq_sync);
437
438 return more_to_do;
439 }
440
scsifront_irq_fn(int irq,void * dev_id)441 static irqreturn_t scsifront_irq_fn(int irq, void *dev_id)
442 {
443 struct vscsifrnt_info *info = dev_id;
444 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
445
446 if (info->host_active == STATE_ERROR) {
447 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
448 return IRQ_HANDLED;
449 }
450
451 while (scsifront_cmd_done(info, &eoiflag))
452 /* Yield point for this unbounded loop. */
453 cond_resched();
454
455 xen_irq_lateeoi(irq, eoiflag);
456
457 return IRQ_HANDLED;
458 }
459
scsifront_finish_all(struct vscsifrnt_info * info)460 static void scsifront_finish_all(struct vscsifrnt_info *info)
461 {
462 unsigned int i, dummy;
463 struct vscsiif_response resp;
464
465 scsifront_ring_drain(info, &dummy);
466
467 for (i = 0; i < VSCSIIF_MAX_REQS; i++) {
468 if (test_bit(i, info->shadow_free_bitmap))
469 continue;
470 resp.rqid = i;
471 resp.sense_len = 0;
472 resp.rslt = DID_RESET << 16;
473 resp.residual_len = 0;
474 scsifront_do_response(info, &resp);
475 }
476 }
477
map_data_for_request(struct vscsifrnt_info * info,struct scsi_cmnd * sc,struct vscsifrnt_shadow * shadow)478 static int map_data_for_request(struct vscsifrnt_info *info,
479 struct scsi_cmnd *sc,
480 struct vscsifrnt_shadow *shadow)
481 {
482 grant_ref_t gref_head;
483 struct page *page;
484 int err, ref, ref_cnt = 0;
485 int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
486 unsigned int i, off, len, bytes;
487 unsigned int data_len = scsi_bufflen(sc);
488 unsigned int data_grants = 0, seg_grants = 0;
489 struct scatterlist *sg;
490 struct scsiif_request_segment *seg;
491
492 if (sc->sc_data_direction == DMA_NONE || !data_len)
493 return 0;
494
495 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
496 data_grants += PFN_UP(sg->offset + sg->length);
497
498 if (data_grants > VSCSIIF_SG_TABLESIZE) {
499 if (data_grants > info->host->sg_tablesize) {
500 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
501 "Unable to map request_buffer for command!\n");
502 return -E2BIG;
503 }
504 seg_grants = vscsiif_grants_sg(data_grants);
505 shadow->sg = kcalloc(data_grants,
506 sizeof(struct scsiif_request_segment), GFP_ATOMIC);
507 if (!shadow->sg)
508 return -ENOMEM;
509 }
510 seg = shadow->sg ? : shadow->seg;
511
512 err = gnttab_alloc_grant_references(seg_grants + data_grants,
513 &gref_head);
514 if (err) {
515 kfree(shadow->sg);
516 shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
517 "gnttab_alloc_grant_references() error\n");
518 return -ENOMEM;
519 }
520
521 if (seg_grants) {
522 page = virt_to_page(seg);
523 off = offset_in_page(seg);
524 len = sizeof(struct scsiif_request_segment) * data_grants;
525 while (len > 0) {
526 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
527
528 ref = gnttab_claim_grant_reference(&gref_head);
529 BUG_ON(ref == -ENOSPC);
530
531 gnttab_grant_foreign_access_ref(ref,
532 info->dev->otherend_id,
533 xen_page_to_gfn(page), 1);
534 shadow->gref[ref_cnt] = ref;
535 shadow->seg[ref_cnt].gref = ref;
536 shadow->seg[ref_cnt].offset = (uint16_t)off;
537 shadow->seg[ref_cnt].length = (uint16_t)bytes;
538
539 page++;
540 len -= bytes;
541 off = 0;
542 ref_cnt++;
543 }
544 BUG_ON(seg_grants < ref_cnt);
545 seg_grants = ref_cnt;
546 }
547
548 scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
549 page = sg_page(sg);
550 off = sg->offset;
551 len = sg->length;
552
553 while (len > 0 && data_len > 0) {
554 /*
555 * sg sends a scatterlist that is larger than
556 * the data_len it wants transferred for certain
557 * IO sizes.
558 */
559 bytes = min_t(unsigned int, len, PAGE_SIZE - off);
560 bytes = min(bytes, data_len);
561
562 ref = gnttab_claim_grant_reference(&gref_head);
563 BUG_ON(ref == -ENOSPC);
564
565 gnttab_grant_foreign_access_ref(ref,
566 info->dev->otherend_id,
567 xen_page_to_gfn(page),
568 grant_ro);
569
570 shadow->gref[ref_cnt] = ref;
571 seg->gref = ref;
572 seg->offset = (uint16_t)off;
573 seg->length = (uint16_t)bytes;
574
575 page++;
576 seg++;
577 len -= bytes;
578 data_len -= bytes;
579 off = 0;
580 ref_cnt++;
581 }
582 }
583
584 if (seg_grants)
585 shadow->nr_segments = VSCSIIF_SG_GRANT | seg_grants;
586 else
587 shadow->nr_segments = (uint8_t)ref_cnt;
588 shadow->nr_grants = ref_cnt;
589
590 return 0;
591 }
592
scsifront_enter(struct vscsifrnt_info * info)593 static int scsifront_enter(struct vscsifrnt_info *info)
594 {
595 if (info->pause)
596 return 1;
597 info->callers++;
598 return 0;
599 }
600
scsifront_return(struct vscsifrnt_info * info)601 static void scsifront_return(struct vscsifrnt_info *info)
602 {
603 info->callers--;
604 if (info->callers)
605 return;
606
607 if (!info->waiting_pause)
608 return;
609
610 info->waiting_pause = 0;
611 wake_up(&info->wq_pause);
612 }
613
scsifront_queuecommand(struct Scsi_Host * shost,struct scsi_cmnd * sc)614 static int scsifront_queuecommand(struct Scsi_Host *shost,
615 struct scsi_cmnd *sc)
616 {
617 struct vscsifrnt_info *info = shost_priv(shost);
618 struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc);
619 unsigned long flags;
620 int err;
621
622 if (info->host_active == STATE_ERROR)
623 return SCSI_MLQUEUE_HOST_BUSY;
624
625 sc->result = 0;
626
627 shadow->sc = sc;
628 shadow->act = VSCSIIF_ACT_SCSI_CDB;
629
630 spin_lock_irqsave(shost->host_lock, flags);
631 if (scsifront_enter(info)) {
632 spin_unlock_irqrestore(shost->host_lock, flags);
633 return SCSI_MLQUEUE_HOST_BUSY;
634 }
635
636 err = map_data_for_request(info, sc, shadow);
637 if (err < 0) {
638 pr_debug("%s: err %d\n", __func__, err);
639 scsifront_return(info);
640 spin_unlock_irqrestore(shost->host_lock, flags);
641 if (err == -ENOMEM)
642 return SCSI_MLQUEUE_HOST_BUSY;
643 sc->result = DID_ERROR << 16;
644 scsi_done(sc);
645 return 0;
646 }
647
648 if (scsifront_do_request(info, shadow)) {
649 scsifront_gnttab_done(info, shadow);
650 goto busy;
651 }
652
653 scsifront_return(info);
654 spin_unlock_irqrestore(shost->host_lock, flags);
655
656 return 0;
657
658 busy:
659 scsifront_return(info);
660 spin_unlock_irqrestore(shost->host_lock, flags);
661 pr_debug("%s: busy\n", __func__);
662 return SCSI_MLQUEUE_HOST_BUSY;
663 }
664
665 /*
666 * Any exception handling (reset or abort) must be forwarded to the backend.
667 * We have to wait until an answer is returned. This answer contains the
668 * result to be returned to the requestor.
669 */
scsifront_action_handler(struct scsi_cmnd * sc,uint8_t act)670 static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act)
671 {
672 struct Scsi_Host *host = sc->device->host;
673 struct vscsifrnt_info *info = shost_priv(host);
674 struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc);
675 int err = 0;
676
677 if (info->host_active == STATE_ERROR)
678 return FAILED;
679
680 shadow = kzalloc(sizeof(*shadow), GFP_NOIO);
681 if (!shadow)
682 return FAILED;
683
684 shadow->act = act;
685 shadow->rslt_reset = RSLT_RESET_WAITING;
686 shadow->sc = sc;
687 shadow->ref_rqid = s->rqid;
688 init_waitqueue_head(&shadow->wq_reset);
689
690 spin_lock_irq(host->host_lock);
691
692 for (;;) {
693 if (scsifront_enter(info))
694 goto fail;
695
696 if (!scsifront_do_request(info, shadow))
697 break;
698
699 scsifront_return(info);
700 if (err)
701 goto fail;
702 info->wait_ring_available = 1;
703 spin_unlock_irq(host->host_lock);
704 err = wait_event_interruptible(info->wq_sync,
705 !info->wait_ring_available);
706 spin_lock_irq(host->host_lock);
707 }
708
709 spin_unlock_irq(host->host_lock);
710 err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset);
711 spin_lock_irq(host->host_lock);
712
713 if (!err) {
714 err = shadow->rslt_reset;
715 scsifront_put_rqid(info, shadow->rqid);
716 kfree(shadow);
717 } else {
718 spin_lock(&info->shadow_lock);
719 shadow->rslt_reset = RSLT_RESET_ERR;
720 spin_unlock(&info->shadow_lock);
721 err = FAILED;
722 }
723
724 scsifront_return(info);
725 spin_unlock_irq(host->host_lock);
726 return err;
727
728 fail:
729 spin_unlock_irq(host->host_lock);
730 kfree(shadow);
731 return FAILED;
732 }
733
scsifront_eh_abort_handler(struct scsi_cmnd * sc)734 static int scsifront_eh_abort_handler(struct scsi_cmnd *sc)
735 {
736 pr_debug("%s\n", __func__);
737 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT);
738 }
739
scsifront_dev_reset_handler(struct scsi_cmnd * sc)740 static int scsifront_dev_reset_handler(struct scsi_cmnd *sc)
741 {
742 pr_debug("%s\n", __func__);
743 return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET);
744 }
745
scsifront_sdev_configure(struct scsi_device * sdev)746 static int scsifront_sdev_configure(struct scsi_device *sdev)
747 {
748 struct vscsifrnt_info *info = shost_priv(sdev->host);
749 int err;
750
751 if (info->host_active == STATE_ERROR)
752 return -EIO;
753
754 if (info && current == info->curr) {
755 err = xenbus_printf(XBT_NIL, info->dev->nodename,
756 info->dev_state_path, "%d", XenbusStateConnected);
757 if (err) {
758 xenbus_dev_error(info->dev, err,
759 "%s: writing dev_state_path", __func__);
760 return err;
761 }
762 }
763
764 return 0;
765 }
766
scsifront_sdev_destroy(struct scsi_device * sdev)767 static void scsifront_sdev_destroy(struct scsi_device *sdev)
768 {
769 struct vscsifrnt_info *info = shost_priv(sdev->host);
770 int err;
771
772 if (info && current == info->curr) {
773 err = xenbus_printf(XBT_NIL, info->dev->nodename,
774 info->dev_state_path, "%d", XenbusStateClosed);
775 if (err)
776 xenbus_dev_error(info->dev, err,
777 "%s: writing dev_state_path", __func__);
778 }
779 }
780
781 static struct scsi_host_template scsifront_sht = {
782 .module = THIS_MODULE,
783 .name = "Xen SCSI frontend driver",
784 .queuecommand = scsifront_queuecommand,
785 .eh_abort_handler = scsifront_eh_abort_handler,
786 .eh_device_reset_handler = scsifront_dev_reset_handler,
787 .slave_configure = scsifront_sdev_configure,
788 .slave_destroy = scsifront_sdev_destroy,
789 .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN,
790 .can_queue = VSCSIIF_MAX_REQS,
791 .this_id = -1,
792 .cmd_size = sizeof(struct vscsifrnt_shadow),
793 .sg_tablesize = VSCSIIF_SG_TABLESIZE,
794 .proc_name = "scsifront",
795 };
796
scsifront_alloc_ring(struct vscsifrnt_info * info)797 static int scsifront_alloc_ring(struct vscsifrnt_info *info)
798 {
799 struct xenbus_device *dev = info->dev;
800 struct vscsiif_sring *sring;
801 int err;
802
803 /***** Frontend to Backend ring start *****/
804 err = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&sring, 1,
805 &info->ring_ref);
806 if (err)
807 return err;
808
809 XEN_FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
810
811 err = xenbus_alloc_evtchn(dev, &info->evtchn);
812 if (err) {
813 xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn");
814 goto free_gnttab;
815 }
816
817 err = bind_evtchn_to_irq_lateeoi(info->evtchn);
818 if (err <= 0) {
819 xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq");
820 goto free_gnttab;
821 }
822
823 info->irq = err;
824
825 err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn,
826 IRQF_ONESHOT, "scsifront", info);
827 if (err) {
828 xenbus_dev_fatal(dev, err, "request_threaded_irq");
829 goto free_irq;
830 }
831
832 return 0;
833
834 /* free resource */
835 free_irq:
836 unbind_from_irqhandler(info->irq, info);
837 free_gnttab:
838 xenbus_teardown_ring((void **)&sring, 1, &info->ring_ref);
839
840 return err;
841 }
842
scsifront_free_ring(struct vscsifrnt_info * info)843 static void scsifront_free_ring(struct vscsifrnt_info *info)
844 {
845 unbind_from_irqhandler(info->irq, info);
846 xenbus_teardown_ring((void **)&info->ring.sring, 1, &info->ring_ref);
847 }
848
scsifront_init_ring(struct vscsifrnt_info * info)849 static int scsifront_init_ring(struct vscsifrnt_info *info)
850 {
851 struct xenbus_device *dev = info->dev;
852 struct xenbus_transaction xbt;
853 int err;
854
855 pr_debug("%s\n", __func__);
856
857 err = scsifront_alloc_ring(info);
858 if (err)
859 return err;
860 pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn);
861
862 again:
863 err = xenbus_transaction_start(&xbt);
864 if (err)
865 xenbus_dev_fatal(dev, err, "starting transaction");
866
867 err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u",
868 info->ring_ref);
869 if (err) {
870 xenbus_dev_fatal(dev, err, "%s", "writing ring-ref");
871 goto fail;
872 }
873
874 err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
875 info->evtchn);
876
877 if (err) {
878 xenbus_dev_fatal(dev, err, "%s", "writing event-channel");
879 goto fail;
880 }
881
882 err = xenbus_transaction_end(xbt, 0);
883 if (err) {
884 if (err == -EAGAIN)
885 goto again;
886 xenbus_dev_fatal(dev, err, "completing transaction");
887 goto free_sring;
888 }
889
890 return 0;
891
892 fail:
893 xenbus_transaction_end(xbt, 1);
894 free_sring:
895 scsifront_free_ring(info);
896
897 return err;
898 }
899
900
scsifront_probe(struct xenbus_device * dev,const struct xenbus_device_id * id)901 static int scsifront_probe(struct xenbus_device *dev,
902 const struct xenbus_device_id *id)
903 {
904 struct vscsifrnt_info *info;
905 struct Scsi_Host *host;
906 int err = -ENOMEM;
907 char name[TASK_COMM_LEN];
908
909 host = scsi_host_alloc(&scsifront_sht, sizeof(*info));
910 if (!host) {
911 xenbus_dev_fatal(dev, err, "fail to allocate scsi host");
912 return err;
913 }
914 info = (struct vscsifrnt_info *)host->hostdata;
915
916 dev_set_drvdata(&dev->dev, info);
917 info->dev = dev;
918
919 bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
920
921 err = scsifront_init_ring(info);
922 if (err) {
923 scsi_host_put(host);
924 return err;
925 }
926
927 init_waitqueue_head(&info->wq_sync);
928 init_waitqueue_head(&info->wq_pause);
929 spin_lock_init(&info->shadow_lock);
930
931 snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no);
932
933 host->max_id = VSCSIIF_MAX_TARGET;
934 host->max_channel = 0;
935 host->max_lun = VSCSIIF_MAX_LUN;
936 host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512;
937 host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE;
938
939 err = scsi_add_host(host, &dev->dev);
940 if (err) {
941 dev_err(&dev->dev, "fail to add scsi host %d\n", err);
942 goto free_sring;
943 }
944 info->host = host;
945 info->host_active = STATE_ACTIVE;
946
947 xenbus_switch_state(dev, XenbusStateInitialised);
948
949 return 0;
950
951 free_sring:
952 scsifront_free_ring(info);
953 scsi_host_put(host);
954 return err;
955 }
956
scsifront_resume(struct xenbus_device * dev)957 static int scsifront_resume(struct xenbus_device *dev)
958 {
959 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
960 struct Scsi_Host *host = info->host;
961 int err;
962
963 spin_lock_irq(host->host_lock);
964
965 /* Finish all still pending commands. */
966 scsifront_finish_all(info);
967
968 spin_unlock_irq(host->host_lock);
969
970 /* Reconnect to dom0. */
971 scsifront_free_ring(info);
972 err = scsifront_init_ring(info);
973 if (err) {
974 dev_err(&dev->dev, "fail to resume %d\n", err);
975 scsi_host_put(host);
976 return err;
977 }
978
979 xenbus_switch_state(dev, XenbusStateInitialised);
980
981 return 0;
982 }
983
scsifront_suspend(struct xenbus_device * dev)984 static int scsifront_suspend(struct xenbus_device *dev)
985 {
986 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
987 struct Scsi_Host *host = info->host;
988 int err = 0;
989
990 /* No new commands for the backend. */
991 spin_lock_irq(host->host_lock);
992 info->pause = 1;
993 while (info->callers && !err) {
994 info->waiting_pause = 1;
995 info->wait_ring_available = 0;
996 spin_unlock_irq(host->host_lock);
997 wake_up(&info->wq_sync);
998 err = wait_event_interruptible(info->wq_pause,
999 !info->waiting_pause);
1000 spin_lock_irq(host->host_lock);
1001 }
1002 spin_unlock_irq(host->host_lock);
1003 return err;
1004 }
1005
scsifront_remove(struct xenbus_device * dev)1006 static int scsifront_remove(struct xenbus_device *dev)
1007 {
1008 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1009
1010 pr_debug("%s: %s removed\n", __func__, dev->nodename);
1011
1012 mutex_lock(&scsifront_mutex);
1013 if (info->host_active != STATE_INACTIVE) {
1014 /* Scsi_host not yet removed */
1015 scsi_remove_host(info->host);
1016 info->host_active = STATE_INACTIVE;
1017 }
1018 mutex_unlock(&scsifront_mutex);
1019
1020 scsifront_free_ring(info);
1021 scsi_host_put(info->host);
1022
1023 return 0;
1024 }
1025
scsifront_disconnect(struct vscsifrnt_info * info)1026 static void scsifront_disconnect(struct vscsifrnt_info *info)
1027 {
1028 struct xenbus_device *dev = info->dev;
1029 struct Scsi_Host *host = info->host;
1030
1031 pr_debug("%s: %s disconnect\n", __func__, dev->nodename);
1032
1033 /*
1034 * When this function is executed, all devices of
1035 * Frontend have been deleted.
1036 * Therefore, it need not block I/O before remove_host.
1037 */
1038
1039 mutex_lock(&scsifront_mutex);
1040 if (info->host_active != STATE_INACTIVE) {
1041 scsi_remove_host(host);
1042 info->host_active = STATE_INACTIVE;
1043 }
1044 mutex_unlock(&scsifront_mutex);
1045
1046 xenbus_frontend_closed(dev);
1047 }
1048
scsifront_do_lun_hotplug(struct vscsifrnt_info * info,int op)1049 static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op)
1050 {
1051 struct xenbus_device *dev = info->dev;
1052 int i, err = 0;
1053 char str[64];
1054 char **dir;
1055 unsigned int dir_n = 0;
1056 unsigned int device_state;
1057 unsigned int hst, chn, tgt, lun;
1058 struct scsi_device *sdev;
1059
1060 if (info->host_active == STATE_ERROR)
1061 return;
1062
1063 dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n);
1064 if (IS_ERR(dir))
1065 return;
1066
1067 /* mark current task as the one allowed to modify device states */
1068 BUG_ON(info->curr);
1069 info->curr = current;
1070
1071 for (i = 0; i < dir_n; i++) {
1072 /* read status */
1073 snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]);
1074 err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u",
1075 &device_state);
1076 if (XENBUS_EXIST_ERR(err))
1077 continue;
1078
1079 /* virtual SCSI device */
1080 snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]);
1081 err = xenbus_scanf(XBT_NIL, dev->otherend, str,
1082 "%u:%u:%u:%u", &hst, &chn, &tgt, &lun);
1083 if (XENBUS_EXIST_ERR(err))
1084 continue;
1085
1086 /*
1087 * Front device state path, used in slave_configure called
1088 * on successfull scsi_add_device, and in slave_destroy called
1089 * on remove of a device.
1090 */
1091 snprintf(info->dev_state_path, sizeof(info->dev_state_path),
1092 "vscsi-devs/%s/state", dir[i]);
1093
1094 switch (op) {
1095 case VSCSIFRONT_OP_ADD_LUN:
1096 if (device_state != XenbusStateInitialised)
1097 break;
1098
1099 if (scsi_add_device(info->host, chn, tgt, lun)) {
1100 dev_err(&dev->dev, "scsi_add_device\n");
1101 err = xenbus_printf(XBT_NIL, dev->nodename,
1102 info->dev_state_path,
1103 "%d", XenbusStateClosed);
1104 if (err)
1105 xenbus_dev_error(dev, err,
1106 "%s: writing dev_state_path", __func__);
1107 }
1108 break;
1109 case VSCSIFRONT_OP_DEL_LUN:
1110 if (device_state != XenbusStateClosing)
1111 break;
1112
1113 sdev = scsi_device_lookup(info->host, chn, tgt, lun);
1114 if (sdev) {
1115 scsi_remove_device(sdev);
1116 scsi_device_put(sdev);
1117 }
1118 break;
1119 case VSCSIFRONT_OP_READD_LUN:
1120 if (device_state == XenbusStateConnected) {
1121 err = xenbus_printf(XBT_NIL, dev->nodename,
1122 info->dev_state_path,
1123 "%d", XenbusStateConnected);
1124 if (err)
1125 xenbus_dev_error(dev, err,
1126 "%s: writing dev_state_path", __func__);
1127 }
1128 break;
1129 default:
1130 break;
1131 }
1132 }
1133
1134 info->curr = NULL;
1135
1136 kfree(dir);
1137 }
1138
scsifront_read_backend_params(struct xenbus_device * dev,struct vscsifrnt_info * info)1139 static void scsifront_read_backend_params(struct xenbus_device *dev,
1140 struct vscsifrnt_info *info)
1141 {
1142 unsigned int sg_grant, nr_segs;
1143 struct Scsi_Host *host = info->host;
1144
1145 sg_grant = xenbus_read_unsigned(dev->otherend, "feature-sg-grant", 0);
1146 nr_segs = min_t(unsigned int, sg_grant, SG_ALL);
1147 nr_segs = max_t(unsigned int, nr_segs, VSCSIIF_SG_TABLESIZE);
1148 nr_segs = min_t(unsigned int, nr_segs,
1149 VSCSIIF_SG_TABLESIZE * PAGE_SIZE /
1150 sizeof(struct scsiif_request_segment));
1151
1152 if (!info->pause && sg_grant)
1153 dev_info(&dev->dev, "using up to %d SG entries\n", nr_segs);
1154 else if (info->pause && nr_segs < host->sg_tablesize)
1155 dev_warn(&dev->dev,
1156 "SG entries decreased from %d to %u - device may not work properly anymore\n",
1157 host->sg_tablesize, nr_segs);
1158
1159 host->sg_tablesize = nr_segs;
1160 host->max_sectors = (nr_segs - 1) * PAGE_SIZE / 512;
1161 }
1162
scsifront_backend_changed(struct xenbus_device * dev,enum xenbus_state backend_state)1163 static void scsifront_backend_changed(struct xenbus_device *dev,
1164 enum xenbus_state backend_state)
1165 {
1166 struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev);
1167
1168 pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state);
1169
1170 switch (backend_state) {
1171 case XenbusStateUnknown:
1172 case XenbusStateInitialising:
1173 case XenbusStateInitWait:
1174 case XenbusStateInitialised:
1175 break;
1176
1177 case XenbusStateConnected:
1178 scsifront_read_backend_params(dev, info);
1179
1180 if (info->pause) {
1181 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_READD_LUN);
1182 xenbus_switch_state(dev, XenbusStateConnected);
1183 info->pause = 0;
1184 return;
1185 }
1186
1187 if (xenbus_read_driver_state(dev->nodename) ==
1188 XenbusStateInitialised)
1189 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1190
1191 if (dev->state != XenbusStateConnected)
1192 xenbus_switch_state(dev, XenbusStateConnected);
1193 break;
1194
1195 case XenbusStateClosed:
1196 if (dev->state == XenbusStateClosed)
1197 break;
1198 fallthrough; /* Missed the backend's Closing state */
1199 case XenbusStateClosing:
1200 scsifront_disconnect(info);
1201 break;
1202
1203 case XenbusStateReconfiguring:
1204 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN);
1205 xenbus_switch_state(dev, XenbusStateReconfiguring);
1206 break;
1207
1208 case XenbusStateReconfigured:
1209 scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN);
1210 xenbus_switch_state(dev, XenbusStateConnected);
1211 break;
1212 }
1213 }
1214
1215 static const struct xenbus_device_id scsifront_ids[] = {
1216 { "vscsi" },
1217 { "" }
1218 };
1219
1220 static struct xenbus_driver scsifront_driver = {
1221 .ids = scsifront_ids,
1222 .probe = scsifront_probe,
1223 .remove = scsifront_remove,
1224 .resume = scsifront_resume,
1225 .suspend = scsifront_suspend,
1226 .otherend_changed = scsifront_backend_changed,
1227 };
1228
scsifront_init(void)1229 static int __init scsifront_init(void)
1230 {
1231 if (!xen_domain())
1232 return -ENODEV;
1233
1234 return xenbus_register_frontend(&scsifront_driver);
1235 }
1236 module_init(scsifront_init);
1237
scsifront_exit(void)1238 static void __exit scsifront_exit(void)
1239 {
1240 xenbus_unregister_driver(&scsifront_driver);
1241 }
1242 module_exit(scsifront_exit);
1243
1244 MODULE_DESCRIPTION("Xen SCSI frontend driver");
1245 MODULE_LICENSE("GPL");
1246 MODULE_ALIAS("xen:vscsi");
1247 MODULE_AUTHOR("Juergen Gross <jgross@suse.com>");
1248